I have an sama5d31-based system with 64MB of memory and a 1920x1080 LVDS display wired for 16-bpp. When I enable legacy fbdev support, the contiguous memory allocator invariably fails with the order-11 allocation for a 1920x1080@24-bpp buffer (~6MB). But this HW can never make any good use of RGB888, so that is a wasted attempt anyway that would also waste precious memory should it succeed. Sure, I could rewrite user-space to go directly to KMS etc, and that makes the (attempted) order-11 allocation go away, replacing it with one order-10 allocation per application restart for a 1920x1080@16-bpp buffer (<4MB). But after a few restarts, order-10 allocations start to fail as well, which is only to be expected AFAIU. So, I'd rather not change user-space (which was originally written to target a smaller display) so that I at the same time get the benefit of an early pre-allocated fbdev frame-buffer that can be reused over and over. But to do that I need to tell the driver that 16-bpp is the preferred depth. Add a module parameter to do just that. Signed-off-by: Peter Rosin <peda@xxxxxxxxxx> --- drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) I found some inspiration regarding naming and implementation here: https://patchwork.kernel.org/patch/9848631/ I have found no feedback on that patch though, which makes me wonder if I'm perhaps barking up the wronig tree? Cheers, Peter diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c index c1ea5c36b006..f0148627c221 100644 --- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c +++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.c @@ -29,6 +29,11 @@ #define ATMEL_HLCDC_LAYER_IRQS_OFFSET 8 +static int atmel_hlcdc_preferred_depth __read_mostly; + +MODULE_PARM_DESC(preferreddepth, "Set preferred bpp"); +module_param_named(preferreddepth, atmel_hlcdc_preferred_depth, int, 0400); + static const struct atmel_hlcdc_layer_desc atmel_hlcdc_at91sam9n12_layers[] = { { .name = "base", @@ -590,6 +595,7 @@ static int atmel_hlcdc_dc_modeset_init(struct drm_device *dev) dev->mode_config.min_height = dc->desc->min_height; dev->mode_config.max_width = dc->desc->max_width; dev->mode_config.max_height = dc->desc->max_height; + dev->mode_config.preferred_depth = 24; dev->mode_config.funcs = &mode_config_funcs; return 0; @@ -658,7 +664,7 @@ static int atmel_hlcdc_dc_load(struct drm_device *dev) platform_set_drvdata(pdev, dev); - drm_fb_cma_fbdev_init(dev, 24, 0); + drm_fb_cma_fbdev_init(dev, atmel_hlcdc_preferred_depth, 0); drm_kms_helper_poll_init(dev); @@ -756,6 +762,16 @@ static int atmel_hlcdc_dc_drm_probe(struct platform_device *pdev) struct drm_device *ddev; int ret; + switch (atmel_hlcdc_preferred_depth) { + case 0: /* driver default */ + case 8: + case 16: + case 24: + break; + default: + return -EINVAL; + } + ddev = drm_dev_alloc(&atmel_hlcdc_dc_driver, &pdev->dev); if (IS_ERR(ddev)) return PTR_ERR(ddev); -- 2.11.0 _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
